What Does NAD+ Do for Your Body?

NAD+ is a coenzyme, a mighty little molecule your cells can't function without. NAD drives energy production, repairs damaged DNA, and keeps your cells talking to each other. 

But it’s in diminishing supply. Your body makes less of it every year. 

By the time you're in your 40s, your NAD+ levels may be less than half of what they were in your 20s, and that drop has real, noticeable effects.

In this article, we’ll explore what NAD does to your body, and the benefits of increasing it.

What is NAD+ and what does it do for your body?

NAD+ stands for nicotinamide adenine dinucleotide. You don't need to remember that—what matters is the job it does.

Every cell in your body runs on energy. NAD+ is what makes that energy conversion possible. It acts as an electron carrier in a process called cellular respiration, shuttling electrons through your mitochondria (your cells' power generators) to produce ATP—the fuel your body actually runs on. 

Without NAD+, your mitochondria can't complete the energy conversion process, which means less ATP, and less of everything that depends on it.

A short list of processes dependent on NAD+ in your body:

A lot depends on NAD.

And a lot depends on it. NAD+ is directly involved in:

• Energy metabolism — converting glucose and fatty acids into usable fuel via the citric acid cycle and oxidative phosphorylation
• DNA repair — fueling PARP enzymes that detect and patch DNA strand breaks caused by UV exposure, oxidative stress, and normal cell division
• Gene expression regulation — activating sirtuins, which control which genes get switched on or off in response to stress, fasting, and aging
• Circadian rhythm — NAD+ levels cycle throughout the day and directly influence the molecular clock that regulates sleep, metabolism, and hormone timing
• Immune response — CD38, an enzyme heavily involved in immune signaling, consumes NAD+ during activation, which is part of why chronic inflammation depletes levels over time
• Cellular communication — NAD+ is a substrate for enzymes that produce signaling molecules involved in calcium regulation and stress response

That's why keeping your levels sufficient matters. When NAD+ is plentiful, all of these systems run well. Your cells make energy efficiently, repair damage quickly, and age more slowly. 

When levels drop, the maintenance slips. Things start to feel off before anything is technically "wrong."

Why do NAD+ levels drop as you get older?

Annoyingly, your body doesn't just make less NAD+ as you age—it also destroys more of it.

An enzyme called CD38 becomes more active as you get older. 

CD38 consumes NAD+ as part of immune signaling, and research has found that CD38 activity increases significantly with age, contributing directly to the decline in cellular NAD+ levels. At the same time, your body's ability to synthesize NAD+ from scratch slows down.

So it’s a double hit: less production, more consumption.

According to a 2020 review published in Nature Reviews Molecular Cell Biology, NAD+ levels can decline by up to 65% with age, depending on the tissue—a drop linked to everything from cognitive decline to metabolic disease.

Lifestyle factors accelerate the decline too. Poor sleep, alcohol, a high-sugar diet, and chronic stress all increase NAD+ consumption through inflammatory pathways, leaving your cells with less to work with.

What does low NAD+ actually feel like?

There's no blood test your primary care doctor will routinely run for NAD+, which means most people don't connect the dots between their levels and how they feel. But the signs tend to cluster in recognizable ways:

• Persistent fatigue that isn't explained by poor sleep or overwork, the kind that makes you feel like you're running on a half-charged battery
• Brain fog — slower thinking, trouble focusing, that feeling of reaching for words
• Poor sleep quality — NAD+ directly regulates the molecular clock that controls your sleep-wake cycle which can show up as trouble falling asleep, lighter sleep, or waking up feeling like you didn't rest
• Slower recovery after exercise, illness, or a bad night's sleep
• Increased sensitivity to stress, less resilience, more reactivity
• General sense that your body just doesn't bounce back the way it used to

None of these are dramatic. That's partly why low NAD+ goes unnoticed for so long. It tends to feel like "just getting older" — until you address it and realize the difference.

Can you actually raise your NAD+ levels?

Yes, and the research on this is still emerging now.

The main options for raising NAD+ levels are oral supplements and intravenous (IV) or injection-based therapy. But they're not equivalent.

Oral supplements have to survive digestion and get absorbed through the gut before they can do anything—and bioavailability (the amount your body actually uses) varies considerably. Then your body has to take those building blocks and create NAD. 

But IV and injection-based NAD+ therapy bypasses that entirely. The NAD+ goes directly into your bloodstream, which means your cells get access to it faster and at higher concentrations.

For people who want measurable, faster results—or who haven't responded well to oral supplements—IV and injection therapy is typically the more effective route.

There's nothing wrong with IV therapy, but it's not always practical. Sitting through an infusion takes time, requires a clinical setting, and isn't something most people can do regularly. Injections deliver NAD+ directly into the bloodstream the same way but on a schedule that's a lot easier to stick to.

Who tends to notice the most benefit from NAD+ support?

The people who tend to see the clearest benefit are:

• Adults 40 and older noticing a shift in energy, recovery, or mental sharpness
• Anyone dealing with chronic fatigue that doesn't have a clear explanation
• People who are physically active and finding their recovery is taking longer than it used to
• Anyone navigating high cognitive demands — demanding jobs, caregiving, sustained focus, who has noticed their mental stamina isn't what it was
• People going through major hormonal shifts, including perimenopause and menopause, where mitochondrial function is already under pressure

If you've been attributing a general decline in how you feel to stress or aging and writing it off, NAD+ injections are worth looking into.

If you're curious whether compounded, off-label NAD+ therapy makes sense for you, Strut's providers can walk you through it — no in-person visit required. Learn more about NAD+ therapy at Strut.

What's the difference between NAD+ supplements and NAD+ IV therapy or injections?

The core difference is delivery — and delivery determines how much NAD+ your cells actually receive.

Oral supplements are convenient, but they have to clear several hurdles: stomach acid, gut absorption, liver processing. By the time the compound reaches your bloodstream, a significant portion has been lost. Some people respond well to oral supplementation; others see minimal effect.

IV NAD+ therapy and NAD+ injections bypass the digestive system entirely. The NAD+ enters your bloodstream directly, which means higher concentrations reach your tissues. This is why people often report noticing effects from IV therapy more quickly and more distinctly than from supplements alone.

For ongoing maintenance, some people use a combination — periodic IV or injection therapy alongside daily oral support. Your provider can help you figure out what makes sense based on your goals and baseline.

NAD+ FAQ

How quickly does NAD+ decline with age? NAD+ levels begin declining in your 40s and drop significantly through midlife. Research suggests levels can fall by roughly 65% between young adulthood and middle age. The decline isn't uniform—factors like sleep, alcohol use, chronic stress, and diet can accelerate it considerably.

Are there any side effects from NAD+ injections? Most people tolerate NAD+ injections well. Some experience mild, temporary soreness at the injection site, and occasional flushing or lightheadedness can occur. These effects are generally short-lived. A qualified provider will walk you through what to expect and adjust your protocol based on how you respond.

How often do you need NAD+ therapy to maintain levels? This varies depending on your baseline, goals, and how your body responds. Some people do an initial series of sessions and then move to monthly maintenance. Others find quarterly therapy is enough to sustain the benefits. Your Strut provider will help you build a protocol based on how you respond.

Does NAD+ actually slow aging? The evidence is promising but still developing. What's well-established is that NAD+ is essential for the cellular processes  like DNA repair, mitochondrial function, sirtuin activation, which are directly linked to how cells age. Whether supplementing NAD+ meaningfully extends lifespan in humans is still being studied. What the research does support is that maintaining adequate NAD+ levels supports the systems that keep cells functioning well as you age.

Ready to find out if off-label, compounded NAD+ therapy is right for you? Strut's medical providers can review your health history and build a personalized plan. All online, no office visit needed. Get started with NAD+ therapy at Strut.